An electronic control device having air ventilation characteristic and water-proof property has been available in a field of automotive parts. In an electronic control device, for example, as disclosed in Japanese Patent Publication No. 2008-78506, a through-hole is formed in a housing of a water-proof structure. A cylindrical pipe portion of an air breathing filter is inserted into the through-hole. A passage formed in the cylindrical pipe portion works as an air ventilation passage. A water-shedding film is attached to the cylindrical pipe portion so as to cover the air ventilation passage, so that air can pass through the water-shedding film but water cannot pass through the water-shedding film from an outside of the housing. In addition, a water-proof sealing member is provided between a flanged portion of the air breathing filter and an outer wall surface of the housing, in order that the water may not enter an inside of the electronic control device via a gap between the air breathing filter and the housing.
In recent years, requirements for the air breathing filter have become higher. In particular, a structure for the air breathing filter, which can withstand a strong external force, is required. For example, since a high-pressure washing machine has been widely used in recent years, water having a strong force may hit against an outside wall of the electronic control device. Therefore, it is necessary for the air breathing filter to maintain high water-proof property even in such a circumstance, in which the high-pressure water is used.
However, in the above conventional air breathing filter, the water-proof sealing member is arranged at an outside of the housing in order to prevent the water from entering the inside of the housing via the gap between the housing and the air breathing filter. In other words, a sealing structure being composed of the water-proof sealing member and its related parts is exposed to the outside of the housing. As a result, the external force (for example, the high-pressure water from the high-pressure washing machine) may be directly applied to the sealing structure.
According to the air breathing filter of the above prior art (JP 2008-78506), the water-proof sealing member (an O-ring 70) is interposed between the flanged portion 53 of the air breathing filter 50 and an outer wall surface of the housing (a flat surface portion 61) in a tight contact condition, in order to prevent the water from entering a small gap formed between an inner wall surface of the through-hole 63 and an outer peripheral surface of the cylindrical pipe portion 55. According to the above structure, however, since the water-proof sealing member (the O-ring 70) and the flanged portion 53 are exposed to the outside of the housing, the external force (such as, the high-pressure water, or the like) is directly applied to the air breathing filter 50. Then, a portion of the air breathing filter 50 neighboring to the water-proof sealing member and/or the flanged portion may be displaced or deformed by such an external force. When such a displacement and/or a deformation occurs, the tight contact condition of the water-proof sealing member is changed to a condition in which the water-proof sealing member is no longer in the tight contact with the outer wall surface of the housing and/or the flanged portion. Then, the water may enter the inside of the housing via such a portion, at which the tight contact condition is lost.